Urine sodium excretion increased slightly among U.S. adults between 1988–2010

摘要

Little information is available on temporal trends in sodium intake in the U.S. population using urine sodium excretion as a biomarker. Our aim was to assess 1988–2010 trends in estimated 24-h urine sodium (24hUNa) excretion among U.S. adults (20–59 y) participating in the cross-sectional National Health and Nutrition Examination Survey (NHANES). We used subsamples from a 1988–1994 convenience sample, a 2003–2006 1/3 random sample, and a 2010 1/3 random sample to comply with resource constraints. We estimated 24hUNa excretion from measured sodium concentrations in spot urine samples by use of calibration equations (for men and women) derived from the INTERSALT study. Estimated 24hUNa excretion increased over the 20-y period (1988–1994, 2003–2006, and 2010) [mean ± SEM (n)]: 3160 ± 38.4 mg/d (1249), 3290 ± 29.4 mg/d (1235), and 3290 ± 44.4 mg/d (525), respectively (Ptrend = 0.022). We observed significantly higher mean estimated 24hUNa excretion in each survey period (P <0.001) for men compared to women (31–33%) and for persons with higher body mass index (BMI) (32–35% for obese vs. normal weight) or blood pressure (–26% for hypertensive vs. normal blood pressure). After adjusting for age, sex, and race-ethnicity, temporal trends in mean estimated 24hUNa excretion remained statistically significant (Ptrend = 0.004). We observed no temporal trends in mean estimated 24hUNa excretion among BMI subgroups, nor after adjusting for BMI. While several limitations apply to this analysis (the use of a convenience sample in 1988–1994 and using estimated 24hUNa excretion as a biomarker of sodium intake), these first NHANES data suggest that mean estimated 24hUNa excretion increased slightly in U.S. adults over the last 2 decades and this increase may be explained by a shift in the distribution of BMI.